Before that users determine the best results using the elements of the search results like the title, URL, and description in each result. Now, this instant preview feature find the best results by seeing the visual presentation.

Google Instant Previews – Benefits

Quickly Compare Results

Pinpoint Relevant Content

Interact with the Results Page

How to make good use of this feature:

Keep your pages clearly laid out and structured

Try to avoid interstitial pages, ad pop-ups, or other elements

Many pages have their previews generated as part of Google regular crawl process.

Instant Previews does not change Google search algorithm or ranking

If you are adding the nosnippet meta tag to your pages will cause them to not show a text snippet in the results.

URLs that have been disallowed in the robots.txt file will also not show Instant Previews.